1. Field of the Invention
The present invention relates to a paper discharge device for a printer, and more particularly to a paper discharge device for a printer adapted to bring paper into elastic contact with a paper discharge roller to apply a carrying force to the paper in the discharge direction.
2. Description of the Prior Art
In FIG. 4 is shown a schematic side elevational view of a conventional paper discharge device. In the paper discharge device shown in the figure, on the upper surface of a base member 2 with a paper feed roller 1 mounted thereon is formed a paper guide surface 3 for guiding paper, which is fed by the paper feed roller 1 in the feed direction (forward) “a”, slidingly toward a print section (not shown in the figure). Extending from a bearing portion 21 of the base member 2, which rotatably supports a spindle 12, in turn supporting the paper feed roller 1, through a longitudinally intermediate position A of the paper guide surface 3, is a paper guide plate 4 with the rear portion thereof raised, the front end portion of the paper guide 4 being brought into elastic contact with the paper guide surface 3 as a paper holding portion 41. Also, a paper discharge roller 5 is provided above the paper feed roller 1, and above the paper discharge roller 5 is provided a paper pressing member 6 in the form of a plate spring, etc., the paper pressing member 6 being brought downward into elastic contact with the circumferential surface 51 of the paper discharge roller 5 by the elasticity thereof. Further, one surface (upper surface) of the paper guide 4 is formed as a paper discharge surface 42 that receives paper carried through on the paper guide surface 3 in front of the paper holding portion 41 in the discharge direction (rearward) “b”, opposite to the feed direction “a”.
In a printer equipped with the paper discharge device having the arrangement above, paper fed by the paper feed roller 1 is held between the paper guide surface 3 and the paper holding portion 41 formed in the front end portion of the paper guide 4 at the longitudinally intermediate position A on the paper guide surface 3, in front of the paper feed roller 1, while the paper passes therethrough in the feed direction “a” to the print section. After printing in the print section, the paper is carried through on the paper guide surface 3 in front of the paper holding portion 41 in the discharge direction “b”. Then, the paper P carried through on the paper guide surface 3 in the discharge direction “b” is raised up by the paper holding portion 41 to run on to the paper discharge surface 42, and subsequently introduced between the paper discharge roller 5 and the paper pressing member 6. Therefore, the paper P is brought downward into elastic contact with the circumferential surface 51 of the paper discharge roller 5 by the elasticity of the paper pressing member 6, and then a carrying force in the discharge direction “b” is applied to the paper P by the paper discharge roller 5 to discharge the paper P rearward.
In such a paper discharge device, in the case where a single motor (not shown in the figure) is used as a rotary drive source for the paper feed roller 1 and the paper discharge roller 5, to limit the required number of motors to one, two examples as shown in FIGS. 5 (A) and 5 (B) can be cited as a transmission mechanism for operating the paper feed roller 1 and the paper discharge roller 5 simultaneously. In the transmission mechanism shown in FIG. 5 (A), a relay gear 73 is provided between an input gear 71 on the side of the paper feed roller 1 and an output gear 72 on the side of the paper discharge roller 5, whereby the paper feed roller 1 and the paper discharge roller 5 are adapted to rotate in the same direction (R1 and R2) respectively to feed and discharge paper without switching the rotational direction of the motor. Meanwhile, in the transmission mechanism shown in FIG. 5 (B), the input gear 71 on the side of the paper feed roller 1 and the output gear 72 on the side of the paper discharge roller 5 are engaged directly with each other, whereby the paper feed roller 1 and the paper discharge roller 5 are adapted to rotate in the opposite directions R1 and R2 respectively to select the feed mode or the discharge mode alternatively by switching the rotational direction of the motor. It is noted that the arrow R1′ indicates the rotational direction of the input gear 71 on the side of the paper feed roller 1 in the feed mode, while the arrow R2′ indicates the rotational direction of the output gear 72 on the side of the paper discharge roller 5 in the feed mode.
Examples of the many paper discharge devices in which paper is brought into elastic contact with a paper discharge roller using a member corresponding to the paper pressing member 6 shown in FIG. 4, and then the paper discharge roller is rotated to apply a carrying force to the paper in the discharge direction, are disclosed in Japanese Utility-Model Laid-Open Publication No. Sho 61-130442, Japanese Patent Laid-Open Publication No. Hei 2-32880, and Japanese Utility-Model Laid-Open Publication No. Hei 6-36850.
However, in the prior art examples shown in FIG. 4 and in the above-mentioned documents, wherein paper is brought into elastic contact with the paper discharge roller 5 using the paper pressing member 6 or a member corresponding thereto, and then the paper discharge roller 5 applies a carrying force to the paper in the discharge direction, requires the paper pressing member 6 or the member corresponding thereto as an additional element, resulting in a cost increase and in a problem in that it is necessary to ensure an additional space for installing the paper pressing member 6, thereby preventing reduction in the size of the paper discharge device.
Also, in the case in the prior art, where with the paper P is introduced over the paper discharge roller 5 and brought downward into elastic contact with the circumferential surface 51 of the paper discharge roller 5 by the paper pressing member 6, the rotary drive source for the paper feed roller 1 and the paper discharge roller 5 is limited to one motor, it is necessary to provide the relay gear 73 between the input gear 71 on the side of the paper feed roller 1 and the output gear 72 on the side of the paper discharge roller 5, shown in to FIG. 5 (A), to feed and discharge paper without switching the rotational direction of the motor, resulting in an increase in the number of required parts and thereby in an increase in the cost and in a problem in that it is necessary to provide an additional space for installing the relay gear 73, preventing the reduction of the size of the paper discharge device. On the other hand, selecting the feed mode and the discharge mode alternatively by switching the rotational direction of the motor suffers from a problem in that the controlling of the rotational direction of the motor becomes complicated.